Thermostatic device



R. P. JACKSON 1,731,420

THERMOSTATIC DEVICE Oct. 15, 1929.

Filed Sept. 9, 1927 INVENTOR Ray P. JacKson :7 ATTORNEY Patented Oct. 15, 1929 UNITED STATES PATENT OFFICE BAY P. JACKSON, 01 BERKELEY, CALIFORNIA, ASSIGNOB '1'0 WESTINGHOUSE ELEC- 'IBIC & MANUFACTURING OOIPANY, A CORPORATION OF PENNSYLVANIA THERHOSTATIC DEVICE Application filed September 9, 1927. Serial No. 218,411.

My invention relates to temperature-responsive devices and particularly "to thermostatic switches of the quick-make-and-break type.

Anobject of my invention is to provide a thermostatic switch that shall be simple in construction, easily manufactured and eflicient in its 0 eration.

Another 0 ject of my invention is to provide a thermostatic element for a switch in 5 justable for operation at any one of a plu-' rality of temperatures, of predetermined" 2o mostatic element, wherebythe points of in-' tions at a predetermined which portions thereof deflect in opposite directions in response to temperature changes.

A further object of my invention is to provide a thermostatic switch that shall be advalues. 4

And a still further object of my invention is to provide means for a reverse-curve ther- .flection may be held in a substantially fixed position.

In practicing my invention, I provide a thermostatic switch that comprises a temper- 25 ature-responsive element having portions thereof adapted to deflect in opposite directions when subjected to tem eratures of predetermined values. The t ermostatic element is provided with means whereby it may be so held that the various portidns thereof are initially flexed in opposite directions. The thermostatic element is provided with contact members for enga ing the flexed por-,

thermostatic element being operable, when another temperature obtains therein, to deflect with a positive snap motion to effect disengagement fromthe contact members.

Means are provided for holding a portion intermediate adjacent to oppositely flexed members of the thermostatic element in a substantially fixed position.

In order that the temperatures at which the thermostatic element shall be operable to engage and disengage the contact members, an

' admsting device is provided for varying the degree of flexure initially obtaining in the thermostatic element. c For a full er understanding of my invention, referencemay be had to the following open-circuit position, and

temperature, the 1 description, taken in conjunction with the accompanymg drawings, in which:

Figure 1 is a front view, in vertical section,

of a thermostatic switch embodying my invention, the switch being shown in'a circuitmaking position,

Fig. 2 is a view of the same device in an Fig. 3 is a top plan view of a ortion of the device illustrated in Figs. 1 an 2.

In the drawings, a thermostatic'switch 11 is illustrated that comprises a base having a body (portion 12 andlug portions 13 and 14 exten ing upwardly therefrom. The base is preferably made of insulating material, although other materials may be utilized, if certain portions thereof are provided with insulating material, as will hereinafter be apparent.

The body portion of the base may be provided with an internally screw-threaded bushing 15 and a bolt 16 that has a screwthread engagement with the bushing. The

inner end of the bolt is provided with a conwith a groove 25 of substantially V-shape that may be in the same plane as the groove 20.

To the lug members 13 and 14 is secured a contact-supporting member 26 of insulating material, the supporting member being secured to the lugs by screws 27 or their equiva lents. The supporting member may be provided with an internally screw-threaded bushing 28 and a screw 29'having a contact member 31 secured to the inner end thereof. The screw 29 has a screw-thread engagement with the bushing 28 and is supported thereby.

In order that the contact members 17 and 31 maybe utilized for controlling an electric in the grooves 20 and 25. The thermostatic element 33 comprises a plurality of bimetallic strips 34 and 35 joined together at 36, preferably by welding, although some other method of securing the adjacent ends of the strips may be utilized, if desired. 1

Inthe device illustrated in the drawings, the high-expansion sides of the strips are joined together, that is, the high-expansion side of the strip 34 is located at 37 and the high expansion side of the strip 35 is located at 38. Thus, the elements tend to deflect or bend in opposite directions when subjected to changing temperatures. 1

In order that the strips 34 and 35 may be held in an initially flexed condition, as shown in' the drawings, the screw 19 is adjusted until the pressure, extending in a longitudinal direction of the thermostatic element 33, is of a predetermined value."

When the longitudinal pressure has been adjusted, the pressure between the contacts 17 and 31 and the strips 35 and 34, respectively, may be adjusted by turning the screws 16 and 29 in the proper directions.

In Fig. 1 of the drawings, the thermostatic strip 34 is bowed upwardly and the strip 35 downwardly to such an extent that contact is made with the contacts 17 and 31. Since;

the strips are bowed in opposite directions,

the thermostatic element 33 may be designated as a reverse-curve thermostatic element having inflection points at 41, 42 and 43.

In order that the point of inflection at 42 may be maintained ina substantially fixed plane with respect to the grooves 20 and 25,

an adjustable pivot member 44, having complemental spaced knife edges 45 and 46, between which the thermostatic element is located, is provided. The pivot member 44 is provided with a flange 48 that extends transversely across an opening 49 in the body portion 12 of the base and a depending lug portion 51 that projects downwardly through the opening.

The member 44 may be held in a predetermined position by means of a plate 52 that extends across the opening 49 and a screw 53. When the member 44 has been placed in a desired position, the screw 53 may be tight ened until the body portion of the base 12 is clamped between the flange 48 and the plate 52.

By means of the adjustable pivot member 44, the point of inflection 42 may be moved towards either the lug 13 or the lug 14, as desired, depending upon the thermal charac: teristic to be obtained by the thermostatic element 33.

When the temperature of the thcrmostatic element 33 is at or below one predetermined value, the strips 34 and 35 normally engage the contacts 17 and 31, but, if the temperature of the thermostatic element is increased to a predetermined higher value, the strips 34 and 35 are caused to so expand that the curvature thereof is reversed, as shown in Fig. 2 of the drawings, thereby effecting disengagement of the strips from the contacts 31 and 17, respectively. When the temperature of the strips 34 and 35 has been reduced to a lower Value, the thermostatic element will assume the position illustrated in Fig. 1 of the drawings, in which position contact is again made between the contacts 17 and 31 and the strips 35 and 34, respectively.

Thus, it is seen that, if the screws 16 and 29 are connected in an electric circuit by means of terminals 55 and 56, the circuit may be controlled in accordance with the thermal condition of the thermostatic element 33.

In order that the temperatures at which the thermostatic element 33 will be caused toassume the respective positions shown in Figs. 1 and 2 may be varied, the longitudinal pres sure exerted on the thermostatic element 33 may be adjusted by means of the screw 19 and the nuts 21 and 22, as hereinbefore set forth. If the devlce' is to be operable to actuate the thermostatic switch to the open-circuit position illustrated in Fig. 2, the longitudinal pressure may be of a relatively low value, but, if the devlce is to be operable at a relatively low temperature, the longitudinal pressure must be increased to a relatively high value. In other words, the temperatures at which the switch 11' is operable to its open and closed-circuit positions is an inverse function of the pressure extending longitudinallyofthe thermostatic element 33.

The temperatures at which the device 11 mostatic switch that comprises a plurality of bimetallic elements so joined together at ad acent ends that tl a respective elements so oined together deflect in opposite directions in response to temperature changes. Means are provided whereby the thermostatic elements'may be held in a flexed condition, the respective elements being flexed oppositely to one another. Contact members are provlded for engagmg the various bimetallic members when the temperature thereof is of a predetermined value, in order that an electric circuit may be controlled inaccordance with the thermal condition of the bimetallic members. Adjusting means are providedalso in order that the temperatures at which an electric circuit to be controlled by the thermostatic switch may be varied over a relatively wide range.

Various modifications may be made in the device embodying my invention without departing from the spirit and the scope thereof. I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and the appended cleaims.

I- claim as my invention:

1. In a thermostatic device, a pair of supports, a plurality of bimetallic members secured together in end-to-end relation and metallic members, means for oining said members at adjacent ends, and means for holding said members in an initially flexed condition.

3. In combination, a plurality of oppositely deflected thermostatic elements joined at adjacent ends, means for supporting said elements in a flexed condition, and means for restraining a portion of said thermostatic elements so joined, intermediate the supports, from lateral movement.

4. In combination, a plurality of supports, a thermostatic eleinent disposed therebetween and supported thereby, said element comprising a plurality of oppositely deflecting bimetallic members having adjacent ends thereof oined together and means for restraining an intermediate portion of said thermostatic element from lateral movement.

5. In combination, a pluralityof supports, a thermostatic element disposed therebetween and supported thereby, said element comprising a plurality of oppositely deflecting bimetallic members having adjacent ends thereof joined together and adjustable means for restraining an intermediate portion of said thermostatic element from lateral movement. 6. In combination, a luralityof supports,

a thermostatic element isposed therebetween and supported thereby, said element comprising a pluralit of. o positely deflecting bimetallic .mem ers Eaving adjacent ends thereof joined together, contact members engageable by said bimetallic members when the temperature thereof is of a predetermined value.

I 7. In combination, a lurality of supports, athermostatic element isposed therebetween and supported thereby, said element comprising' a pluralityof oppositely deflecting bimetallic members having adjacent ends thereof joined tggether, and means for restraining an interim iate portion of said thermostatic element from lateral movement.

8. In a thermo-responsive device, a lural ity of supports, a thermostatic strip ocated therebetween'and restrained from longitudinal movement, said stri comprising a plurality of oppositely eflecting bimetallic members joined end to end, contact members normally engaging said bimetallic members, said members being disengageable from the contact members witha snap motion when a temperature of a'predetermined value obtains therein.

9. In a thermo-responsive device, a plurality of supports, a thermostatic element supported thereby, said element comprising a plurality of oppositely deflecting bimetallic members joined end to end, means for causing said members to be normally flexed in opposite directions, and means for restraining a portion of said thermostatic elements intermediate its ends from lateral movement between the supports.

10. In a thermostatic device, a thermostatic member comprising a plurality of oppositely deflecting elements joined together, means for holding the thermostatic member in a normally flexed position and means for varying the flexure thereof.

11. In a thermostatic device, a thermostatic member comprising a plurality of oppositely deflected elements joined together, means for holding the thermostatic member normally in a flexed position, and means for restraining a portion of said thermostatic member intermediate its length from lateral movement.

12. A -thermostatic device comprising a plurality of bimetallic elements joined together at adjacent ends, the adjoining elements being positioned to flex in opposite directions in response to changes in tempera-- ture, and'means for holding said bimetallic members in a flexed condition.

13. A thermostatic device comprising a pluralit of bimetallic elements joined together at a jacent ends, the adjoining elements being positioned to flex in opposite directions in response to changes in temperature and pressure, means for holding sald bimetallic elements in a flexed condition.

14. A thermostatic device comprising a thermostatic element having a plurality of reversely curved bimetallic portions and means for holding the points of inflection of said element substantially fixed.

oppositely tflexed bimetallic portions and means for adjusting the flexure of said portions.

17. A thermostatic device comprising a 5 thermostatic element having a plurality of oppositely flexed portions, means for adjusting the flexure of said portions, and contact members for cooperating with said portions between the points of inflection. I 1 In testimony whereof, I have hereunto subscribed my name this 30th day of August,

RAY P. J AOKSON. 

